Heroin laced with the painkiller fentanyl may be responsible for recent overdoses reported throughout the state, a high concentration of which have been in New London and Litchfield counties, state police said Saturday.

State police have issued a "dangerous drug threat alert" in which they warned that fentanyl is 100 times more potent than morphine. While New London and Litchfield counties have seen a greater number of overdoses, similar instances of drug overdoses have been reported throughout New England and the tri-state area, police said.

Fentanyl is prescribed to cancer patients to treat pain and may cause serious harm or death if not used properly, according to the National Institutes of Health.

State police detectives in the Statewide Narcotics Task Force are working to identify the source or sources of heroin laced with fentanyl in Connecticut.

Anyone with any information is asked to contact local or state police. All calls will be kept confidential.